SNAP Trial Finds Common Antibiotic Cefazolin Matches Standard Treatment for Serious Blood Infection

A major international clinical trial published in the New England Journal of Medicine has found that cefazolin performs as well as flucloxacillin or cloxacillin in treating a potentially fatal bloodstream infection, and causes fewer kidney-related side effects.

What the Trial Found

The New England Journal of Medicine has published results from the SNAP trial, a clinical study examining how best to treat methicillin-susceptible Staphylococcus aureus bacteraemia — a serious bacterial infection of the bloodstream that can be life-threatening if not treated promptly.

Staphylococcus aureus bacteraemia, sometimes called staph bacteraemia, occurs when the Staphylococcus aureus bacterium enters the blood. The methicillin-susceptible form means the infection can still be treated with certain antibiotics, unlike the more widely known MRSA strain.

The Core Finding: Two Drugs, Similar Outcomes

According to the trial results, cefazolin — an antibiotic already widely used in clinical settings — was found to be noninferior to flucloxacillin or cloxacillin when measuring 90-day mortality. In plain terms: patients treated with cefazolin were no more likely to die within 90 days than those treated with the drugs currently considered standard care.

That alone would be a notable finding. But the trial also recorded fewer nephrotoxic effects — meaning less kidney damage — among patients receiving cefazolin. Kidney injury is a recognised risk with several antibiotic treatments, and reducing that risk without compromising survival outcomes matters clinically.

The NEJM posted the findings directly, linking to both the full trial results and a Research Summary for clinicians and interested readers.

Why Antibiotic Choice Matters

Choosing the right antibiotic for bloodstream infections isn’t straightforward. Clinicians must weigh effectiveness against side-effect profiles, patient tolerance, local resistance patterns, and drug availability. Flucloxacillin has long been the preferred agent in the UK for methicillin-susceptible staph infections; cefazolin is more commonly used in North America and parts of Europe.

If cefazolin produces equivalent survival outcomes with a lower risk of kidney harm, that could influence prescribing decisions — above all for patients who are already vulnerable to renal complications, such as older adults or those with pre-existing kidney conditions.

Questions Still to Answer

The trial results, as reported by the NEJM, present the headline findings. But clinicians and researchers will want to examine the full data — including patient demographics, dosing regimens, infection sources, and any subgroup differences — before drawing firm conclusions about how these results should shape practice in the UK. NHS antibiotic prescribing guidelines are overseen nationally, and any changes to recommended treatment pathways would require review by relevant bodies including NHS England and NICE.

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Key Takeaways

• The SNAP trial found cefazolin was noninferior to flucloxacillin or cloxacillin for 90-day mortality in patients with methicillin-susceptible Staphylococcus aureus bacteraemia
• Patients treated with cefazolin experienced fewer nephrotoxic — kidney-damaging — effects than those on the comparator drugs
• Full trial results and a Research Summary have been published in the New England Journal of Medicine

What This Means for Kent Residents

Patients in Kent being treated for serious bloodstream infections are cared for under NHS Kent and Medway, which follows national prescribing guidelines set by NHS England and NICE. This trial does not change current treatment protocols, and anyone concerned about an infection or their prescribed medication should speak to their GP or call NHS 111 before making any decisions. For a medical emergency — including symptoms of severe infection such as high fever, rapid breathing, or confusion — always call 999 immediately.